PROJECT SUMMARY (Project 5 - Bhattacharyya, Ormsbee) Due to their relative chemical stability and ubiquitous nature, chlorinated organic compounds such as polychlorinated biphenyls (PCBs) and trichloroethylene (TCE) continue to pose both remediation challenges and human health risks. At many Superfund sites, past remediation efforts using traditional treatment strategies (e.g., reactive barriers, six phase heating, etc.) have proven to be highly costly and largely ineffective. Alternative strategies include both reductive and oxidative pathways for chloro-organic degradation to non-toxic compounds. The development of nanosized iron-based materials has brought important and promising techniques into the field of environmental remediation. In recent years, zero-valent nanoscale metal (especially iron) particles have attracted growing attention in groundwater remediation of chlorinated solvents. For more rapid and complete reductive dechlorination, a second metal is often added, resulting in bimetallic nanoparticles. In the past, utilization of such approaches at actual Superfund sites has been limited due to concerns about particle agglomeration or release into the environment. Project 5 will address the need for targeted remediation strategies by developing integrated, cost-effective technologies which incorporate both reductive and oxidative strategies in order to allow the complete remediation of chlorinated organic compounds without the production of toxic byproducts Three specific aims are to: 1) create a porous, common polymer membrane immobilized platform for synthesis of reactive and stable iron-based nanoparticles using environmentally safe approaches to prevent aggregation and loss of particles; 2) embed immobilized nanoparticles in responsive membrane domain to allow highly effective PCB and TCE dechlorination by both reductive and oxidative approaches; 3) determine whether PCB demineralization with reduction by bimetallic (iron and palladium) nanoparticles as a first step, followed by oxidation with iron oxide nanoparticles immobilized in polymer membrane domain, will eliminate the formation of toxic chlorine-substituted intermediates, as verified by toxicity tests. To accomplish the aims, a polymer/ membrane platform will be developed in both lab scale and full-scale for environmentally benign nanostructured iron synthesis, and individual and combined technology strategies will be established to reduce the toxicity of chloro-organics (selected PCBs and chloroethylenes). The proposed approach should address the agglomeration and toxicity concerns associated with the use of bimetallic nanoparticles and allow for the complete breakdown of chlorinated organic compounds to nontoxic and biodegradable intermediates. The project will include collaborations with the U.S. Environmental Protection Agency's (EPA's) National Risk Management Research Laboratory focused on nanoparticle synthesis and characterization using EPA facilities. As in the past, the project will work with diverse primary stakeholders at state and federal levels to implement the developed technologies at the Paducah Gaseous Diffusion Plant, Kentucky largest Superfund site.